Abstract
Bioactive glasses caused a revolution in healthcare and paved the way for modern biomaterial-driven regenerative medicine. The first 45S5 glass composition, invented by Larry Hench fifty years ago, was able to bond to living bone and to stimulate osteogenesis through the release of biologically-active ions. 45S5-based glass products have been successfully implanted in millions of patients worldwide, mainly to repair bone and dental defects and, over the years, many other bioactive glass compositions have been proposed for innovative biomedical applications, such as soft tissue repair and drug delivery. The full potential of bioactive glasses seems still yet to be fulfilled, and many of today’s achievements were unthinkable when research began. As a result, the research involving bioactive glasses is highly stimulating and requires a cross-disciplinary collaboration among glass chemists, bioengineers, and clinicians. The present article provides a picture of the current clinical applications of bioactive glasses, and depicts six relevant challenges deserving to be tackled in the near future. We hope that this work can be useful to both early-stage researchers, who are moving with their first steps in the world of bioactive glasses, and experienced scientists, to stimulate discussion about future research and discover new applications for glass in medicine.
Highlights
The Invention of Bioactive GlassThe need to replace damaged parts of the body in order to restore their physiological functionality has always been the driving force which has supported research into the discovery and the design of new biomaterials, in order to perform this task as efficiently as possible.After the initial definition of biomaterial, based on the criterion of maximum biochemical/biological inertness in contact with body fluids [1], the discovery of 45S5 Bioglass® by Hench in 1969 [2] constituted—for the first time in the story of biomaterials—an alternative
After being implanted, metals are prone to be encapsulated within fibrous tissue in the body; on the contrary, bioactive glasses (BGs) coatings have the potential to improve the implant stability by bonding it to the host bone and to protect the metallic
After being implanted, metals are prone to be encapsulated within fibrous tissue in the body; on the contrary, BG coatings have the potential to improve the implant stability by bonding it to the host bone and to protect the metallic substrate from corrosion, avoiding the release of toxic metal ions in vivo [64]
Summary
The need to replace damaged parts of the body in order to restore their physiological functionality has always been the driving force which has supported research into the discovery and the design of new biomaterials, in order to perform this task as efficiently as possible. From 1969 to 1971, Hench and his coworkers designed and studied different glass formulations based on the SiO2–Na2O–CaO–P2O5 oxide system, and they selected the composition 45SiO2–24.5Na2O–24.5CaO–6P2O5 (wt %), characterized by high amounts of Na2O and CaO, as well as a relatively high CaO/P2O5 ratio that makes the surface of the material very reactive in physiological environment [6]. This glass composition, referred to as 45S5, had the advantage of being extremely easy to melt, due to its proximity to the ternary eutectic. The interested reader is addressed to a valuable work published by Jones, who summarized the evolution of research about BGs over the last decades [14]
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